The present invention relates generally to semiconductor devices and, more particularly to a structure for a power metal-oxide-semiconductor-field-effect-transistors (MOSFETs).
The terms metal-oxide-semiconductor (MOS) and field-effect-transistor (FET), and the combination “MOSFET” have come into common use in the electronics arts for insulated gate field effect transistors (IGFETs) even though they may use any type of dielectric for the gate insulator and not just oxide insulators, and any type of conductor for the gate electrode not just metals. Accordingly, unless otherwise specifically noted, as used herein, the term “metal” in connection with MOSFETs is intended to include any type of conductor. Non-limiting examples of such conductors are metallic conductors, semi-metal conductors, alloy conductors, doped and undoped semiconductors, and mixtures and combinations thereof. Similarly, unless otherwise specifically noted, the term “oxide” in connection with MOSFETs is intended to include any type of organic or inorganic dielectric. Non-limiting examples of such dielectrics are oxide dielectrics, nitride dielectric, fluoride dielectrics, plastic materials and other types of inorganic and organic dielectrics as well as mixtures and combinations thereof. Further, the abbreviations MOSFET and IGFET and the terms for which they stand are used interchangeably herein.
Power MOSFETs are much used in electronic circuits and their utility depends on their properties and cost. Great effort has been expended and continues to be expended in improving their properties, manufacturing efficiency and cost, and there is an ongoing need for further improvements. Such improvements are crucially dependent on the structure and methods of manufacture of such MOSFETs.